docs: def _process_environment_cvterm(self):
          """
          This is the mapping between the internal environment id
          and the external ones; here we map the internal environment id to
          the external one in the hashmap.
          :return:
  
          """
  
          line_counter = 0
          raw = '/'.join((self.rawdir, 'environment_cvterm'))
          LOG.info("processing environment to cvterm mappings")
  
          with open(raw, 'r') as f:
              f.readline()  # read the header row; skip
              filereader = csv.reader(f, delimiter='\t', quotechar='\"')
              for line in filereader:
                  line_counter += 1
  
                  (environment_cvterm_id, environment_id, cvterm_id) = line
                  # 1	1	60468
  
                  environment_key = environment_id
  
                  cvterm_key = cvterm_id
                  cvterm_id = self.idhash['cvterm'][cvterm_key]
  
                  # look up the dbxref_id for the cvterm
                  # hopefully it's one-to-one
                  self.idhash['environment'][environment_key] = cvterm_id
  
          return